At least that's the idea. The Nordtvedt effect has been tested, and so far no evidence has been found that the more massive Earth is falling towards the sun faster than the moon. If there is an effect, it's very slight.

So some guy had an idea, but there's no evidence it's correct. In fact, it seems to be wrong. This is truly game changing.

St_Francis_P:At least that's the idea. The Nordtvedt effect has been tested, and so far no evidence has been found that the more massive Earth is falling towards the sun faster than the moon. If there is an effect, it's very slight.

So some guy had an idea, but there's no evidence it's correct. In fact, it seems to be wrong. This is truly game changing.

Kome:St_Francis_P: At least that's the idea. The Nordtvedt effect has been tested, and so far no evidence has been found that the more massive Earth is falling towards the sun faster than the moon. If there is an effect, it's very slight.

So some guy had an idea, but there's no evidence it's correct. In fact, it seems to be wrong. This is truly game changing.

St_Francis_P:Kome: St_Francis_P: At least that's the idea. The Nordtvedt effect has been tested, and so far no evidence has been found that the more massive Earth is falling towards the sun faster than the moon. If there is an effect, it's very slight.

So some guy had an idea, but there's no evidence it's correct. In fact, it seems to be wrong. This is truly game changing.

That is how science works.

It is, but usually it doesn't become a featured article afterward.

Actually science journalism is almost dead in America.

Even Perez Hilton posting famous women on his shiatty blog and calling them whores is more insightful and educational these days.

NASA only releases rocks and CGI generated deep field "photographs" and the same speculations we've had since the 70's.

Quantum is so misunderstood you can just skip any article about it and save what little you might know from driving you insane.

New products using centuries old conepts with an LED attached are masquraded as "progress"

And, if you wait around, once every day some jackass asks "Whar flying car, whar?" and sells it to a newspaper as an editorial.

Even Perez Hilton posting famous women on his shiatty blog and calling them whores is more insightful and educational these days.

NASA only releases rocks and CGI generated deep field "photographs" and the same speculations we've had since the 70's.

Quantum is so misunderstood you can just skip any article about it and save what little you might know from driving you insane.

New products using centuries old conepts with an LED attached are masquraded as "progress"

And, if you wait around, once every day some jackass asks "Whar flying car, whar?" and sells it to a newspaper as an editorial.

I really want to try my hand at writing science journalism, since I seem to actually have a knack for explaining some difficult aspects of science in an understandable way.

I was, somehow, able to explain time dilatation in a coherent fashion to a pre-vet student. At a weekend camp we were both councilors at, surrounded by 60 screaming children. Without being able to use drawings or math: only gestures and the 'light clock on a train' explanation. .. she later came back and said my explanation caused her physics 2306 class to suddenly make sense and enabled her to pass.

/Also, I have a really, really good visual analogy/demonstration for why we care about nanophysics/how simply changing the *size* of an object can drastically alter its properties....

Felgraf:doglover: Actually science journalism is almost dead in America.

Even Perez Hilton posting famous women on his shiatty blog and calling them whores is more insightful and educational these days.

NASA only releases rocks and CGI generated deep field "photographs" and the same speculations we've had since the 70's.

Quantum is so misunderstood you can just skip any article about it and save what little you might know from driving you insane.

New products using centuries old conepts with an LED attached are masquraded as "progress"

And, if you wait around, once every day some jackass asks "Whar flying car, whar?" and sells it to a newspaper as an editorial.

I really want to try my hand at writing science journalism, since I seem to actually have a knack for explaining some difficult aspects of science in an understandable way.

I was, somehow, able to explain time dilatation in a coherent fashion to a pre-vet student. At a weekend camp we were both councilors at, surrounded by 60 screaming children. Without being able to use drawings or math: only gestures and the 'light clock on a train' explanation. .. she later came back and said my explanation caused her physics 2306 class to suddenly make sense and enabled her to pass.

/Also, I have a really, really good visual analogy/demonstration for why we care about nanophysics/how simply changing the *size* of an object can drastically alter its properties....

Alas, my field is nanophysics (though a grey goo scenario is... well, in my opinion, kiiinndaa vanishingly unlikely. And even if it is possible, we're so far away from that being a possibility it's not even funny!), so I cannot help you there.

That said, we ARE sort of living in the future. =) And we DO almost have friggen tricorders (Seriously, think of all the capabilities smartphone has! Now keep in mind there are people trying to develop cheap attatchmentss that would allow you to use one *as a spectrometer*).

lordargent:The Nordtvedt effect has been tested, and so far no evidence has been found that the more massive Earth is falling towards the sun faster than the moon. If there is an effect, it's very slight.

So an unproved theory, wake me up when you have actual data that supports the theory.

At least that's the idea. The Nordtvedt effect has been tested, and so far no evidence has been found that the more massive Earth is falling towards the sun faster than the moon. If there is an effect, it's very slight. But if it's there, everything we know about motion, and even relativity, changes. Wouldn't that be cool?

Sure. You know what else would be cool? If it turned out that there were actually invisible angel unicorns pushing things together, instead of some weird mysterious "gravity". Think of all the things we could convince those invisible angel unicorns to do! So far, there's no evidence that they exist. Still, I should totally write an article about them.

St_Francis_P:Kome: St_Francis_P: At least that's the idea. The Nordtvedt effect has been tested, and so far no evidence has been found that the more massive Earth is falling towards the sun faster than the moon. If there is an effect, it's very slight.

So some guy had an idea, but there's no evidence it's correct. In fact, it seems to be wrong. This is truly game changing.

Well, of course it does. This is kinda like how Newton was mostly right unless you're traveling at relativistic speeds and what not. For objects of extremely low mass, like everything we deal with every day, the pull exerted on the Earth is so negligible that it really isn't even necessary to consider it, thus everything accelerates at about the same rate, +- 10-30 m/s or whatever the actual error would be. It's really the mass difference between the two objects that matter when disregarding the smaller mass, so the Earth or Moon compared to the Sun is like a 20 pound cannonball or a 10 pound cannonball compared to Earth.

Otherwise, the actual equation for acceleration due to gravity is F= G * ((m1 * m2) / r2), which makes it quite obvious that both masses effect acceleration. If a second Earth mass planet magically popped up nearby, the rate at which it would accelerate towards the Earth would be at least twice that of a much less massive object, like the cannonball. Well, really, this second planet would accelerate towards the earth at the usual rate we're used to, but the Earth would also accelerate towards this second planet by the same amount, thus from the reference point of the Earth (and all reference points must be valid), the second planet would be accelerating twice as fast as a much less massive object.

The second two concepts are two different views of mass. There's inertial mass. Imagine an object is on perfectly greased wheels on a perfectly smooth, level floor. If you were to reach out and push it, you would have to exert enough force to move its inertial mass.

Nope, sorry, you're wrong. If this object was on perfectly greased wheels on a perfectly smooth, level floor, no matter how lightly you pushed it, it would begin to accelerate. It just might accelerate very slowly if it's very massive.

Drop a small marble against a heavy bowling ball. Initially they will accelerate at the same rate, yes. But because the bowling ball is heavier, the Earth will accelerate toward it slightly faster. Because it accelerates slightly faster toward the ball, the radius between the two gets lower faster, and because the radius is lower the acceleration of gravity is greater, therefore the bowling ball falls faster. QED

St_Francis_P:Kome: St_Francis_P: At least that's the idea. The Nordtvedt effect has been tested, and so far no evidence has been found that the more massive Earth is falling towards the sun faster than the moon. If there is an effect, it's very slight.

So some guy had an idea, but there's no evidence it's correct. In fact, it seems to be wrong. This is truly game changing.

That is how science works.

It is, but usually it doesn't become a featured article afterward.

Io9 is hardly qualifies as a "featured article" in academic circles. It's probably more embarrassing to be on io9 than get rejected from a crappy conference.

Newton invented calculus while trying to model gravity pushing. He wanted to calculate how each tiny part of each object would be pushed towards the other object. I still find it an interesting experiment because if you model the pushing force as to be very high, very fine and very unlikely, the sums do mirror the much simpler formula that works so well and it also works for inertia. It is also an interesting way to teach people how to think of developing their own mathematics to solve new problems as well as dealing with edge cases where things do end up differently between observed and the theory.

Smeggy Smurf:I always figured the object with the greater mass fell faster because the more massive object's additional gravity helped things along

If you have two items of the same size and weight but one has a denser core, it will fall faster because pull of he side of the higher density areas is closer to the center line in theory. It would take some impressive equipment to do that experiment and get any useful data since a fall of meters might have fall times that differ far less than a trillionth of a second.

Wow, old news is exciting! Nordtvedt has been at this for decades. I used a lot of his work in my undergrad research project. For further reading, check out my advisor's 2000 paper: http://arxiv.org/abs/gr-qc/0007047 I worked to try to extend that paper to other solar system bodies. I made some progress, but it was a dead end and another student has picked it up and is heading in a slightly different direction.

The basic idea is that many "beyond the standard model" proposals introduce a field that couples to matter differently than gravity. Perhaps nuclear binding energy plays a role. Perhaps it's proton to neutron ratio. There are many proposed fields out there. Now, just as gravity is far weaker than electromagnetism, this proposed field is much weaker than gravity, so any effects would be very small. It is already constrained to the 1 part in 1013 by lunar laser ranging and torsion balances. That still leaves plenty of room for a new field to hide.

There have been a few satellite projects proposed to measure this effect even more sensitively. Some of the Gravity Probe B guys are working on STEP (Satellite Tests of the Equivalence Principle) which would theoretically be able to measure any deviation to one part in 1018. The Europeans are working on a project called MICROSCOPE that will work similarly. These satelliteexperiments wouldn't be terribly expensive, but unfortunately, big projects like the JWST take up all of the funding.

Smeggy Smurf:I always figured the object with the greater mass fell faster because the more massive object's additional gravity helped things along

The object with the greater mass feels a greater force, yes. However, because it's more massive, it takes more force to accelerate it at the same rate as a smaller mass. It's actually very fascinating that there are two types of mass, and as far as we can tell, they're exactly the same. Mass is the gravitational "charge." It's what determines how strong a gravitational field is. It's ALSO what causes resistance to acceleration. At first glance, these two things should have nothing to do with one another. The fact that they are equal is one of the foundations of Einstein's general relativity.

DON.MAC:If you have two items of the same size and weight but one has a denser core, it will fall faster because pull of he side of the higher density areas is closer to the center line in theory. It would take some impressive equipment to do that experiment and get any useful data since a fall of meters might have fall times that differ far less than a trillionth of a second.

Gauss's law disagrees with you. Unless you can break out some math, I do believe that the theoretical difference in the rate of falling is 0.

jack21221:DON.MAC: If you have two items of the same size and weight but one has a denser core, it will fall faster because pull of he side of the higher density areas is closer to the center line in theory. It would take some impressive equipment to do that experiment and get any useful data since a fall of meters might have fall times that differ far less than a trillionth of a second.

Gauss's law disagrees with you. Unless you can break out some math, I do believe that the theoretical difference in the rate of falling is 0.

I'm guessing that the zero you talk about is a good round number. I'm guessing the real difference would be something on the order of one test sphere having one more atom than the other but my second guess would be the ratio of the difference would be something in the order of 1 to 10-75.

The heavier mass might have a greater force acting on it, but that force is trying to accelerate a greater mass. If you want keep the acceleration rate the same and have increased the mass the amount of force applied must also be increased.

Then again the physics of planets is all theory anyway. The math might be sound, but it isn't like you can really measure things planet sized.

I had this same thought in high school 20 years ago when I read about Newton's Law of Universal Gravitation... from which you can derive the basically the same thing without having to go to all the trouble to make a new name for it with an unnecessary 'd' paired up with 't's.That pesky general relativity probably explains this too, but It's too late for me to internet deep dive long enough to understand what the fark a tensor is.